Mass compensating system drives are known which include at least one balance shaft, generally two, for compensating forces and/or moments of inertia of a reciprocating piston internal combustion engine. The balance shaft rotates within a housing of two to three journals that contain either plain or rolling bearings. The bearings are typically lubricated by pressurized splash or mist oil.
U.S. Pat. No. 6,305,339 discloses a balance shaft for a mass compensating system drive for an internal combustion engines. The balance shaft has unbalanced masses arranged on both sides of a journal, while the journal projects significantly in the radial direction past the shaft sections adjacent to the journal within a part of the periphery that is diametrically opposite the unbalanced masses.
U.S. Pat. No. 6,971,361 discloses a balance shaft mounted via rolling bearings on its journals. Lubrication here also appears to be provided by a mist of lubricating oil in the associated area of the engine block or housing.
US 2008/0053753 discloses a balance shaft module using plain bearings to support the balance shafts. The bearings are lubricated by the engine oil system which provides a flow of lubricating oil to the bearing journal. However, no regulation of the oil flow is provided.
It would be desirable to provide a flow of lubricating oil to the journals of a balance shaft of a mass compensating system drive that can be regulated depending on conditions, such as engine speed, in order to ensure proper lubrication for long life.